Neutra

Neutra

A neutral place where people's AI assistants agree on things for them, without anyone seeing anyone else's data.

Today it does one thing: two people's assistants find a time to meet. Each assistant tells Neutra when its person is free. Neutra finds a common time and sends one calendar invite to both. Neither side ever sees the other's times.

sequenceDiagram    participant A as Anna's assistant    participant N as Neutra    participant B as Ben's assistant    A->>N: Anna's free times    N-->>A: a message for Anna to forward to Ben    Note over A,B: Anna forwards it in any chat    B->>N: Ben's free times + the code    N-->>A: calendar invite    N-->>B: calendar invite

It works across assistants: Anna can use Claude and Ben another assistant, as long as both support MCP connectors. Ben can also answer without an assistant: the message includes a link to a simple page where he signs in with Google and adds the times he's free.

Privacy, by design

• No AI on Neutra's side. Neutra is plain code that compares time ranges. Your times never go into an AI model of ours.
• Nobody sees anyone's times. Only the matched meeting time comes back. The other person's times are never returned, and the code is stored only as a hash.
• Times are deleted as soon as a decision is settled, at the latest after 14 days. The person answering never has their times stored at all.
• Retries can't map a calendar. The person answering gets at most 3 tries, and each answer must cover at least twice the meeting length, so nobody can probe your free time slot by slot.
• Data stays in the EU, in Cloudflare's EU jurisdiction.
• Checked by tests: test/decisions.test.ts verifies that no times or codes appear in any response.

Details: privacy page.

Try it

1. In Claude: Customize → Connectors → Add custom connector, URL https://neutra.day/mcp, then Add.
2. Sign in with Google. Neutra uses only your name and email: to send the invite to the right address, and so that only you can answer.
3. Ask: "Use Neutra to find an hour with Ben next week. I'm free Tuesday and Thursday, 18:00–21:00." Forward the message it gives you.

For agent builders

A remote MCP server with Google sign-in. Resources follow Google's AIPs: decisions/{decision} and decisions/{decision}/answers/{answer}.

Errors use google.rpc codes: NOT_FOUND, PERMISSION_DENIED, FAILED_PRECONDITION, INVALID_ARGUMENT, RESOURCE_EXHAUSTED (a daily or hourly limit was reached).

Running Neutra

Runs on Cloudflare Workers with D1, based on Cloudflare's remote-mcp-google-oauth template. Every push to main is type-checked, tested and deployed by GitHub Actions (.github/workflows/deploy.yml); migrations in migrations/ are applied before each deploy. Changes go through pull requests.

Setup (done once)

Cloudflare

• Account ID and the MCP_RESOURCE address are in wrangler.jsonc. The domain neutra.day is attached to the Worker as a Custom Domain in the Cloudflare dashboard.
• API token: "Edit Cloudflare Workers" template plus D1: Edit.
• The D1 database (EU jurisdiction) and the OAUTH_KV namespace were created once with wrangler d1 create neutra --jurisdiction eu and wrangler kv namespace create OAUTH_KV; their IDs are in wrangler.jsonc.

Google Cloud (project neutra)

• Google Auth Platform: audience External, publishing status In production (testing mode makes refresh tokens expire after 7 days). Branding: home page and privacy links above, authorized domain neutra.day.
• Web client with redirect URI https://neutra.day/callback, used by both the connector sign-in and the browser answer page (add https://developers.google.com/oauthplayground only while making a new inviter key, and http://localhost:8788/callback for local dev).
• Google Calendar API and Gmail API enabled.
• Sign-in asks only for email and profile. While ACCESS_MODE is allowlist, only ALLOWED_EMAILS can sign in.

Inviter ([email protected])

• Refresh token with scopes calendar.events and gmail.send, obtained via the OAuth 2.0 Playground using the web client's own credentials (steps in docs/RUNBOOK.md).

GitHub secrets (Settings → Secrets and variables → Actions)

Local development

npm install, copy .dev.vars.example to .dev.vars and fill it in, then npm run dev. Test with npx @modelcontextprotocol/inspector@latest against http://localhost:8788/mcp.

License

MIT, see LICENSE. Includes code from Cloudflare's MIT-licensed templates.